LIGHTING & CO₂

CO₂ Diffuser

Ceramic or in-line device that dissolves CO₂ into fine bubbles the water can absorb.

Planting stage Lighting

Unplug before servicingHands out of the water firstDrip loop on every cableTest before you dose30 ppm CO₂ ceilingCycle before stocking

Lighting

Specification
Type	In-tank ceramic or in-line
Pore size	0.5–2 µm
Bubble size	0.1–0.5 mm
Working pressure	1–2.5 bar
Hose fit	4/6 mm or 12/16 mm
Replacement disc	Available separately

Technical parameters
Dissolution efficiency	70–95% in-line
In-tank mist	Visible, cosmetic
Cleaning interval	1–2 weeks
Scale removal	Dilute bleach soak
Pressure rise	Signals clogging
Position	Low in tank, under flow

CO₂ only enters the water where gas and water touch. A diffuser creates that contact area by forcing gas through a fine ceramic disc, producing a stream of microbubbles that dissolve as they rise.

Two designs dominate. An in-tank ceramic diffuser sits on the glass and produces the finest bubbles, which is the most efficient for dissolution but leaves a visible mist in the water — many aquascapers consider this acceptable or even attractive. An in-line diffuser fits into the return hose of a canister filter and mixes gas into a high-flow water stream, dissolving it out of sight with no mist in the display.

The trade-off is maintenance. Ceramic pores clog with biofilm and mineral scale, and a clogged diffuser needs more pressure to push the same gas, which shows up as a rising working pressure on the regulator gauge. A weekly scrub and an occasional soak in a diluted bleach solution keeps it working; always rinse thoroughly afterwards.

Safety and welfare

Rinse any bleach solution off a ceramic disc with at least ten minutes of running water before it goes back in the tank. Residual bleach will kill livestock.
Relieve pressure at the regulator before disconnecting any CO₂ hose.
An in-line diffuser must be fitted in the return line, never the intake, or gas collects in the canister and can airlock the pump.

Using it well

Place the diffuser low and beneath the filter outflow so bubbles are swept around the tank instead of rising straight to the surface.

If bubble production drops, the disc is clogged, not the regulator. Clean the disc before touching the needle valve.

An in-line diffuser on a canister gives the cleanest-looking tank. An in-tank one gives the finest bubbles. Choose based on which compromise you prefer.

Works with

CO₂ regulatorBubble counterCanister filterDrop checker

Note. Parameters are conventional ranges across the category, not the claim of any one manufacturer. Nothing on this page is for sale and no outcome for any plant or animal is guaranteed. Simulator output elsewhere on this site is a simplified model, not a measurement — confirm everything with a test kit and the equipment's own instructions.

CO₂ Diffuser

Using it well

Works with

Works alongside